Impact drill insert with frustum cutters

ABSTRACT

An impact drill for both reciprocation and rotation to drill into a surface and provided with a plurality of frustum cutters. The frustum cutters are arranged in one or more arrays and are spaced radially from the axis of rotation of the drill and are spaced axially from the tip of the drill.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to the drilling art and more particularly to an improved impact drill arrangement provided with a plurality of frustum cutters.

[0003] 2. Description of the Prior Art

[0004] There have often been utilized impact drilling tools which are adapted to provide holes or apertures in various materials. Such impact drilling tools have a driving portion which is coupled to an insert having a cutter bit thereon to both rotate and reciprocate the insert during the drilling operation. Often the inserts in such impact drilling tools utilized in the past had a comparatively short operational life due to the dulling of the cutting bits employed and/or the actual fracture of the cutting bits. That is, the forces exerted on the cutting bits by both the axial reciprocation causing repeated impacting on the material to be drilled as well as the forces exerted on the cutting bits by the rotation about the longitudinal axis of the tool in the engagement with the material to be drilled during the drilling limited the useful life of such tools.

[0005] The advent of the frustum cutter has provided a type of cutter which resists the damages caused during a cutting and/or drilling operation thus providing exceptionally long operational life to the various cutting, drilling, boring, milling and other tools in which such frustum cutters were utilized. However, there has not heretofore been provided in an impact drill an arrangement of frustum cutters which will have the desired long operational life. Thus, there has long been a need for an impact drilling tool in which an insert may be employed and the insert has a cutter head having a plurality of frustum cutters thereon.

SUMMARY OF THE INVENTION

[0006] It is an object of the present invention to provide an improved impact drill arrangement having a drilling insert with an increased operational life.

[0007] It is another object of the present invention to provide an impact drill arrangement having a plurality of frustum cutters coupled to the drilling insert.

[0008] It is yet another object of the present invention to provide an impact drill arrangement that resists damage an/or dulling of the drilling insert during the intended use thereof.

BRIEF DESCRIPTION OF THE DRAWING

[0009] The above, and other objects of the present invention are illustrated in the accompanying drawing wherein similar reference characters refer to similar elements throughout and in which:

[0010]FIGS. 1, 2 and 3 illustrate a first preferred embodiment of the present invention;

[0011]FIGS. 4 and 5 illustrate a second preferred embodiment of the present invention; and

[0012]FIGS. 6, 7 and 8 illustrate a third preferred embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Referring now to the drawing there is illustrated in FIGS. 1, 2 and 3 a first preferred embodiment of the present invention generally designated 10. In the embodiment 10 there is provided a drilling insert body member 12 having a shank portion 14 which is adapted to be inserted into the drilling tool (not shown) so as to be both rotated and reciprocated thereby. The insert 12 is also provided with a cutting head portion 16. The cutting head portion 16 is provided with a plurality of three frustum cutters 18, 20 and 22 mounted thereon to have an axis of each in skew relationship to the central axis of rotation 24 and are at an equal radial distance from the central axis 24. The angle of the skew relationship of each of the frustum cutters 18, 20 and 22 is, in the preferred embodiments of the present invention the same so that the corresponding impact/cutting portions of each of the frustum cutters 18, 20 and 22 simultaneously contact the material to be drilled for the condition of the cental axis 24 perpendicular to the material to be drilled.

[0014] For the condition of the central axis 24 at an angle to the material to be drilled, one of the frustum cutters 18, 20 and 22 will first contact the material to be drilled. Each of the frustum cutters 18, 20 and 22 may be of the general frustum cutter configuration as taught in patent U.S. Pat. No. 4, 621, 955. However, in the embodiment 10, the frustum cutters 18, 20 and 22 are fixed to the body member 12 and do not rotate with respect thereto. Consequently, the frustum cutters 18, 20 and 22 are single ended rather than the double ended configuration as shown in patent U.S. Pat. No. 4,621,955. The frustum cutters 18, 20 and 22 are mounted on the body member 14 so that the impact/cutting portions thereof which first contact the material to be drilled are coplanar in a plane substantially perpendicular to the axis of rotation.

[0015] The embodiment 10 is also provided with a pilot drill 26, which may be a twist drill as shown or a spade drill as described below that is aligned with the central axis 24 and the insert 12 penetrates the material to be drilled a first preselected depth determined by the axial length of the pilot drill 26 before there is contact of the frustum cutters with the material to be drilled.

[0016]FIGS. 4 and 5 illustrate a second embodiment generally designated 40 of the present invention which is generally similar to the embodiment 10 except that there are provided six frustum cutters arrayed in two orientations on the insert body member 12′. The first plurality of frustum cutters 42, 44, 46 and 48 in a first array and each have an axis that is skew with respect to the central axis 24 and are located at a first preselected radial distance from the central axis 24. The second plurality of frustum cutters 52 and 54 are in a second array and each have an axis that is skew with respect to the central axis 24 and are located at a second preselected radial distance from the central axis 24. The second preselected radial distance is less that the first preselected radial distance. Each of the frustum cutters 42, 44, 46 and 48 of the first array and the frustum cutters 50 and 52 of the second array may be of the same general configuration as the frustum cutters in embodiment 10 and may be generally as taught in U.S. Pat. No. 4,621,955 and are mounted on the insert body member 12′ so that the impact/cutting portions thereof are coplanar in a plane substantially perpendicular to the axis of rotation. The skew angles of the frustum cutters 42, 44, 46 and 48 of the first array are the same and the skew angles of the frustum cutters 50 and 52 of the second array are the same. In the preferred embodiments the skew angles of the frustum cutters in the first array are the same as the skew angles of the frustum cutters in the second array. However, it may be desirable in some applications to have the skew angles of the first array of frustum cutters different than the skew angles of the frustum cutters of the second array.

[0017] The embodiment 40 is provided with a spade drill 54 aligned with the central axis 24 instead of the pilot drill 26 of embodiment 10. It will be appreciated that either a spade drill or pilot drill may be used in any embodiment of the present invention depending upon the particular requirements of the intended use thereof. The operation of the insert 12′ is similar to the operation of the insert 12 described above. For the condition of the central axis 24 perpendicular to the surface of the material to be drilled the insert 12′ penetrates into the material to be drilled a first preselected depth defined by the axial length of the spade drill 54 prior to the time that the corresponding impact/cutting portions of the frustum cutters of the first and second arrays contact the material to be drilled.

[0018] Referring now to FIGS. 6, 7 and 8 there is shown an embodiment generally designated 60 of the present invention which is generally similar to the embodiments 10 and 40 described above. In the embodiment 60 there is an insert body member 12″ on which are provided ten frustum cutters aligned in a first array and a second array. The first array has five frustum cutters 62, 64, 66, 68 and 70 each having an axis that is skew with respect to the central axis 24 and spaced a first preselected radial distance from the central axis 24. The skew angle of the axes of the frustum cutters 62, 64, 66, 68 and 70 are preferably the same. The second array has five frustum cutters 72, 74, 76 78 and 80 each having an axis that is skew with respect to the central axis 24 and spaced a second preselected radial distance from the central axis 24. The second preselected radial distance is less than the first preselected radial distance. The skew angle of the axes of the frustum cutters 72, 74, 76, 78 and 80 are preferably the same and, in preferred embodiments of the present invention are the same as the angle of the skew axis of the first array. Each of the frustum cutters in the first and the second array may be of the general frustum cutter configuration as taught in patent U.S. Pat. No. 4,621,955.

[0019] The embodiment 60 is provided with a pilot drill 26 similar to the pilot drill 26 of embodiment 10.

[0020] In operation of each of the embodiments 10, 40 and 60 described above, the drilling insert 12, 12′ and 12″ is adapted to be inserted into a tool holder (not shown) of the type that both rotates the insert 12, 12′ and 12″ about the central axis 24 thereof as well as reciprocating the insert 12, 12′ and 12″ in axial directions along the central axis 24. The rotational rate and the reciprocating rate may be selected by the user as determined by the material being drilled, the size of the insert 12, 12′ and 12″ and other factors well known to those skilled inn the art. In general, it is preferred that the rotation of the insert 12, 12′ and 12″ and the reciprocation of the insert 12, 12′ and 12′ be simultaneous. That is, the insert 12, 12′ and 12″ is both reciprocated and rotated during the drilling operation. Thus, the pilot drill 26 of embodiment 10, the spade drill 54 of embodiment 40 and the pilot drill 26 of embodiment 60 generally makes the first contact with the material to be drilled. As the insert 12, 12′ and 12″ is rotated and reciprocated the frustum cutters come into contact with the material to be drilled and the cutting or drilling operation continues until the insert reaches a predetermined depth, which is determined by the depth to which the pilot drill or spade drill of the insert penetrates and the frustum cutters contact the material to be drilled. Further reciprocation and rotation provides the desired drilled condition of the material to be drilled.

[0021] In the embodiments 10, 40 and 60 described above, the plurality of frustum cutters have the impact/cutting portions thereof in a plane so that when the insert reaches the predetermined depth after the pilot drill or spade drill has penetrated the material to be drilled, all of the frustum cutters simultaneously engage the material to be drilled. However, in some applications it may be desirable to have the different arrays of cutters at different axial positions on the insert. That is, for example, the second plurality of frustum cutters 50 and 52 in the second array may be positioned closer axially to the tip of the spade drill 54 so that the frustum cutters 50 and 52 first engage the material to be drilled after the insert has penetrated the material to be drilled the preselected depth. Further penetration of the insert results in the plurality of frustum cutters 42, 44, 46 and 48 of the first array then contacting the material to be drilled. Thus, the impact/cutting portions of the frustum cutters 50 and 52 are coplanar in a first plane perpendicular to the central axis 24 and the impact/cutting portions of the frustum cutters 42, 44, 46 and 48 lie in a second plane perpendicular to the axis 24 and the second plane is spaced a greater distance from the spade drill 54 than the first plane containing the impact/cutting portions of the frustum cutters 50 and 52. A similar arrangement may be made of the two arrays of frustum cutters in the embodiment 60 by having the impact/cutting portions of the five frustum cutters 72, 74, 76, 78 and 89 of the second array in a first plane perpendicular to the central axis closer to the pilot drill 26 than a plane containing the impact/cutting portions of the five frustum cutters 62, 64, 66, 68 and 70 of the first array.

[0022] In other preferred embodiments of the present invention, the number of arrays of frustum cutters maybe greater than two and may be as many as desired for particular applications. Similarly, the number of frustum cutters in each array may selected as required for particular applications and may be greater than two arrays as illustrated in embodiments 40 and 60.

[0023] This concludes the description of the preferred embodiments of the present invention. The appended claims are intended to cover all variations and adaptations of the invention falling within the true scope and spirit thereof. 

What is claimed is:
 1. An improved impact drill insert with frustum cutters and adapted to be simultaneously rotated and reciprocated and comprising, in combination: an insert body member having a shank portion, a cutting head portion and a central axis; a pilot drill mounted on said cutting head portion and aligned with said central axis and having a preselected pilot drill axial length; a first plurality of frustum cutters in a first array mounted on said cutting head portion of said insert body member and said first plurality of frustum cutters having corresponding impact/cutter portions lying in planes perpendicular to said central axis and spaced axially from said pilot drill; each of said frustum cutters in said first plurality in said first array having an axis at a predetermined skew angle with respect to said central axis and each of said frustum cutters in said first plurality radially spaced from said central axis.
 2. The arrangement defined in claim 1 wherein: said skew angle of each of said axis of each of said frustum cutters is the same.
 3. The arrangement defined in claim 1 wherein: said skew angle of each of said axis of each of said frustum cutters is different.
 4. The arrangement defined in claim 2 wherein: said corresponding impact/cutter portions of each of said frustum cutters lie in the same plane perpendicular to said central axis.
 5. The arrangement defined in claim 1 wherein: the number of said first plurality of frustum cutters in said first array is three.
 6. The arrangement defined in claim 1 wherein: each of said first plurality of frustum cutters in said first array is at the same radial spacing from said central axis.
 7. The arrangement defined in claim 1 wherein: each of said first plurality of frustum cutters in said first array is at the same axial spacing from said pilot drill.
 8. The arrangement defined in claim 1 and further comprising: a second plurality of frustum cutters in a second array mounted on said cutting head portion of said insert body member and said second plurality of frustum cutters having corresponding impact/cutter portions lying in planes perpendicular to said central axis and spaced axially from said pilot drill; each of said frustum cutters in said second plurality in said second array having an axis at a predetermined skew angle with respect to said central axis and each of said frustum cutters in said second plurality radially spaced from said central axis and radially spaced from said first plurality of frustum cutters in said first array.
 9. The arrangement defined in claim 8 wherein: the number of frustum cutters in said first plurality of frustum cutters is different from the number of frustum cutters in said second plurality of frustum cutters.
 10. The arrangement defined in claim 8 wherein: the number of frustum cutters in said first plurality of frustum cutters is the same as the number of frustum cutters in said second plurality of frustum cutters.
 11. The arrangement defined in claim 8 wherein: said skew angle of said axis of each of said frustum cutters in said first plurality of frustum cutters is the same; said skew angle of said axis of each of said frustum cutters in said second plurality of frustum cutters is the same; and, said skew angle of said axis of each of said frustum cutters in each of said first plurality of frustum cutters and said second plurality of frustum cutters is the same.
 12. The arrangement defined in claim 8 wherein: said skew angle of said axis of each of said frustum cutters in said first plurality of frustum cutters is the same; said skew angle of said axis of each of said frustum cutters in said second plurality of frustum cutters is the same; and, said skew angle of said axis of each of said frustum cutters in said first plurality of frustum cutters is different from said skew angle of said axis of each of said second plurality of frustum cutters.
 13. The arrangement defined in claim 8 wherein: said corresponding impact/cutter portions of each of said frustum cutters in each of said first plurality of frustum cutters and said second plurality of frustum cutters lie in the same plane perpendicular to said central axis.
 14. The arrangement defined in claim 8 wherein: said first plurality of frustum cutters and said second plurality of frustum cutters are axially spaced from said pilot drill the same axial distance.
 15. The arrangement defined in claim 8 wherein: said first plurality of frustum cutters is spaced a first axial distance from said pilot drill and said second plurality of frustum cutters are spaced a second axial distance from said pilot drill and said first axial distance is less than said second axial distance.
 16. The arrangement defined in claim 8 wherein: the number of said frustum cutters in said first plurality of frustum cutters is two and the number of said frustum cutters in said second plurality of frustum cutters is four.
 17. The arrangement defined in claim 8 wherein: the number of said frustum cutters in said first plurality of frustum cutters is five and the number of said frustum cutters in said second plurality of frustum cutters is five.
 18. An improved impact drill insert with frustum cutters and adapted to be simultaneously rotated and reciprocated and comprising, in combination: an insert body member having a shank portion, a cutting head portion and a central axis; a pilot drill comprising one of a twist drill and a spade drill mounted on said cutting head portion and aligned with said central axis and having a preselected pilot drill axial length; a first plurality of frustum cutters in a first array mounted on said cutting head portion of said insert body member and said first plurality of frustum cutters having corresponding impact/cutter portions lying in planes perpendicular to said central axis and spaced axially from said pilot drill; each of said frustum cutters in said first plurality in said first array having an axis at a predetermined skew angle with respect to said central axis and each of said frustum cutters in said first plurality radially spaced from said central axis; a second plurality of frustum cutters in a second array mounted on said cutting head portion of said insert body member and said second plurality of frustum cutters having corresponding impact/cutter portions lying in planes perpendicular to said central axis and spaced axially from said pilot drill; each of said frustum cutters in said second plurality in said second array having an axis at a predetermined skew angle with respect to said central axis and each of said frustum cutters in said second plurality radially spaced from said central axis and radially spaced from said first plurality of frustum cutters in said first array; each of said frustum cutters in said first plurality of said frustum cutters in said first array spaced a first radial distance from said central axis and spaced a first axial distance from said pilot drill; each of said frustum cutters in said second plurality of said frustum cutters in said second array spaced a second radial distance from said central axis and said second radial,distance is greater than said first radial distance, and spaced said first axial distance from said pilot drill;\ said axis of each of said frustum cutters in said first plurality of frustum cutters at a first skew angle with respect to said central axis and said axis of each of said frustum cutters in said second plurality of frustum cutters at a second skew angle with respect to said central axis; said corresponding impact/cutter portions of each of said frustum cutters in said first array and each of said frustum cutters in said second array lie in a plane perpendicular to said central axis.
 19. The arrangement defined in claim 18 wherein: aid pilot drill is a twist drill.
 20. The arrangement defined in claim 18 wherein: said piolot drill is a spade drill. 